ECB Wades Into Currency Wars But Needs Reform Backing

President Mario Draghi is Taking Some Big Gambles

The European Central Bank spent a long time being a noncombatant in the global currency wars. But it has decisively entered the fray as it seeks to boost its balance sheet by €1 trillion ($1.294 trillion) through fresh loans and securities purchases.

The strength of the euro has bedeviled the eurozone, weighing on inflation and complicating efforts of crisis-hit nations to rebalance their economies. But now the tide has turned. The euro has fallen more than 10 cents against the dollar since May. Thursday, it racked up its...